mirage/mirage: PR #1540: internal: Fix off-by-one locations in mirage/main.ml

@6bb6446

Stages:

• 🟡 x86_64-debian-10-4.13
• ✔️ arm64-debian-10-4.13 (9m14s)

History:

• 17/05/2024 15:14 🟡 @098c6f8 (5m13s)
• 17/05/2024 15:10 🟠 @ee7a4a4 (4m16s)
• 17/05/2024 13:40 🟡 @6bb6446 (9m14s)
• 17/05/2024 13:29 ✔️ @fca83d1 (10m30s)